Plotting board



refs. 16, 1954 H. G; OCH ET AL 2,669,500

PLOTTING BOAR Filed June 26, 1946 16 Sheets-Sheet l CLOUD SWITCH A ,7 ALTITUDE 2/ cowmrzn smrcu 70/ ALTITUDE CONVERTER ELEVA TION 25 lll PIC ALT! TUDE 0141.5 DEV/CE F/G. l2

A 7' TORNE Y H, G. ocH ETAL Feb. 16, 1954 PLOTTING BOARD 16 Sheets-Sheet 2 Filed June 26, 1946 A VVV RANGE k SPOT NETWORK FOR Y COORDINA TE NETWORK F OR H COORDINATE INVENTORS:

mace/1 aaPA /mvso/v BY a ATTORNEY Feb. 16, 1954 H. G. OCH ET AL PLOTTING BOARD Filed June 26, 1946 SECOND DERIVATIVE NETWORK FOR Y COORDINA TE SECOND DERIVATIVE NETWORK FOR H COORDINATE 16 Sheets-Sheet 4 HGZOC'H INVENTORS.

wavy-n ATTORNEY Feb. 16, 1954 H. G. ocH ET AL 2,669,500

PLOTTING BOARD Filed June 26, 1946 16 Sheets-Sheet 5 11.0. 0c WVENTORS'D. a. PARK/NSON ATTORNEY Feb. 16,1954 H. G. OCH ET AL 2,669,500

PLOTTING BOARD Filed June 26, 1946 16 Sheets-Sheet 6 I 887 889 FIG. 9

1116.00! 'aamnx/usow A 7 TORNE Y Feb. 16, T954 H. G. OCH ET AL PLOTTING BOARD Filed June 26, 1946 16 Sheets-Sheet 7 saw H. a. 00/ INVENTORS- 0. a. mn/r/mso/v wdom ATTORNEY Feb. 16, 1954 H. G. OCH ET AL PLOTTING BOARD l6 Sheets-Sheet 10 Filed June 26, 1946 H. 6. DC IN V N 0. B. PARK/NSON ATTORNEY Feb. 16, 1954 H. G. OCH ET AL H. 6.06/1 IN T093- 0. a. PARK/N50 I ATTORNEY 16 Sheets-Sheet 12 ATTORNEY INVENTORS= Feb. 16, 1954 Filed June 26, 1946 Feb. 16, 1954 H. s. OCH ET AL PLOTTING BOARD 16 Sheets-Sheet 13 Filed June 26, 1946 MEN KEN HGOCH WVE/VTORS- o. a. PARK/NSO/V ATTORAJEV Feb. 16, 1954 H. G. OCH ET AL PLOTTING BOARD Filed June 26, 1946 16 Sheets-Sheet 14 uaom lNl 0. a. PAR/(INSON ATTORNEY Feb. 16, 1954 G QCH ET AL 2,669,500

PLOTTING BOARD Filed June 26, 1946 1e Sheets-Sheet 15 FIG. 24

H. a. 004 "WE/V T0951 0. a. PARKINSON ATTORNEY H. G. OCH ET AL Feb. 16, 1954 I PLOTTING BOARD 16 Sheets-Sheet 16 Filed June 26. 1946 #aocn W VENTOPS o. a. PARKINSON ATTR/VEV Patented Feb. 16, 1954 UNITED- s'rsrss m1? I 2.369500:

BIIO'fi'iiNG BOARD Henny GisOch, slime Hills, ass nav'i sort. Maplewoum-i N t-L, assig'nbi s" to phone Laboratories}Incorporated; New. York;- N- Y aicorporation of NeW'York Application Jimeae'; 1946,.S erialN6; mitts?" invention relates toplotting board's a'ssociated with gun data computers';

The" obj'ect of the: invention is" means for con tinuously plotting in rectangularcoordinates the present: and predicted future-position of a target tothe-largest convenient scalein any-'map square within; range ofitne guns and for martina the plotted traces at corresponding points.

Armatureor? the: invention is a; plurality or pens: for? plotting the positions of the target;-

means for interchanging the functions or the pens to match the direction of movement of the: target and means for centering: thepens at desired: points on" theplotting surface to cheeii thee-adjustment ofltheipenss Anothen feature oil the invention niean's f displacing the plotted area to represent any map square within range of the guns.

Another feature of the'invention is means for displacing the origin of the plotted values from the interior of the plotting surface tifone edgewith an appropriatechange in the scale factor of the plotted values.

A further feature of the invention is means for manually or automatically marking theplotted' traces at corresponding; desired points for easy identification QfsimiIari points on the traces,

thus indicating any errors in the observation of? the target or the prediction of the future posi tion of the target. H

The invention is diselosediimcombination with a gun data computer equipped with spot controls, facilities for manuallyisettinglin-the target rates in the coordinates and means'for predicting the motion of the target along curved courses. From the plotted values of the actual and predicted courses of the-target, and theiresultsattained by the fire of the guns, .theioperators may estimate what type and amount 'of correction should he made to attain successful. results.

Other features andjadvantagesof the invention;

willhe apparent from the specification anddraw ings, in which-1,.

Fig. 1 schematically shows the observing equipment;

Fig. 2 schematically shows. a summing am? pliflerf Eig. 3i.shows amplifiers .associate'diwitlf 1 Fig.5; 4 'schematicallyi shoWsth'e .fiirstlderivative andsmoothing networks;

Fig. 5" schematically shows. the: targeti ratemeters and apparatus for supplyingiquantiti'es proportional to hand set rates;

Fig. 6 schematically shows the second derivative and smoothing. networks;

cry,

10*. fcii miniiiiirigpibamendcards sssetiatea wiainie iii showth'ef comp e I Figsia sncws the -reiiiiiiirsiiips dr Figs. 1 te i ie and- Fig'si- 13A; 1312; 13c;-

uiagraiiii iaiieasiy" emetriearrelaubishipsiiivbwea;i {i Eige ais-atbpwiewmra mam-assteiated wi the cemiiuieiiwini pleitiiigairs libr i'zon tal pesition of the target;

Eig i 1E is ai-perspeetive vievr of the horizontal ,7 Fi 17; and-w ti'oii aibiig iihe i a "4 associated with" the omputer", f or plotting tli verticarposititri oi tiie tareetz y I Fig. 24 is a partial end viwattire-bearsShawn iii-Piece; v H

Iris-25, zsareisiueiviws in pait'of'the" ensi seu witiithebeard oirig: la'nii,--

needed that potii ticiiietr res coiiii cteato the slant'di s; taifce sh'aft"of'a'radanand is moved by the shaft to select a voltagewith respect to grounw pron pOrti'GnaLTtE th'e slant distance and-is connected through resistor 5, connection 6 and resistor tit,

hj a; resistor and the; ind iiig..;isi of "potentiometer errand-ground; The brush .of

Fig. 3, to the input circuit of amplifier 302, of the type shown in Fig. 2.

If an optical range finder is used, a synchronous transmitter driven by the slant distance shaft of the range finder is connected to the synchronous receiver 1, Fig. 1. The receiver drives the center dial 8, of three concentric dials 8, 9, I0. The motor I I, through the speed reducing device l2 and gears l3 drives the outer dial Ill. The operator adjusts the device [2 until the dial is turning in synchronism with the dial 8.

A grounded source of power 10 is connected through resistor l5 and the winding GM of potentiometer PTB to ground. The brush of potentiometer PTG is connected to the device l2 and is moved to select a voltage with respect to ground proportional to the slant distance. This brush is connected through resistor l8, connection 6 and resistor 3i 5, Fig. 3, to the input circuit of amplifier 302.

When either of the brushes of potentiometers PT3 or PTB, of Fig. 1, is in use, the other brush is preferably disconnected, or rotated to the grounded end of the associated winding.

The amplifier shown in Fig. 2 employs three vacuum tubes 225, 221, 228 having the usual cathodes, heated by heater elements connected to a suitable source of power (not shown). The vacuum tube 226 is preferably a twin triode having the cathode connected through a variable resistor 204 and resistor 205 to ground. A grounded source of positive potential 206 is connected to the anode, and the control electrode is connected to the junction of resistors 204, 205. As disclosed in United States Patent 2,308,997, January 19, 1943, S. E. Miller, this connection stabilizes the twin triode against variations in cathode emission.

The input terminal 200 is connected to the control electrode of the left-hand section of the twin triode 226. The anode of this section is connected to the control electrod of thepentode 221 by an interstage coupling network, of the type disclosed in United States Patent 1,751,527, March 25, 1930, H. Nyquist, including resistors 201 208, 4

200 and the sources of power 2), 2| l. Resistor H2 and capacitor 2l3, connected in serial relationship across the input circuit of pentode 22l, correct for any phase shifts in the amplifier due to parasitic capacitances.

The cathode and suppressor grid of the pentode 22'! are connected toground, and the screen grid is connected to a grounded source of power 214.

The anode of the pentode 221 is coupled to the control grid of the beam power vacuum tube 223 by a coupling network including resistors 2 I5, 2 l B, 2 I l and the sources of power 2l8, 2 l 9.

The cathode, and beam screen, of the tube 228 are connected to the negative pole of the grounded source of power 220. The screen grid is grounded through resistor 22!. connected through resistor 222, to the positive pole of the grounded source of power 223.

The biasing voltage applied tothe control electrode of tube 228, the resistance of resistor 222 and the magnitudes of'the potentials of the sources 220, 223 are so selected that, when no signal voltage is applied to the input terminal 200, these elements form a balanced bridge and no potential difference will be produced across the output terminals 224, 225. If desired, a potentiometer (not shown) may be connected to supply a small adjustable potential to the input terminal .200 so that, in the absence of a signal voltage applied to the terminal 200, the potential difference be- The anode is 4 tween the output terminals 224, 225 may be adjusted precisely to zero.

A potential divider, such as the winding of a potentiometer, or two resistors in series, may be connected across the output terminals 224, 225. The brush of this potentiometer, or the junction of the resistors, is connected to the input terminal 200 through a resistor ro. If the full output potential is to be applied to the feedback path, the potential divider may be omitted, and resistor 10 connected directly from terminal 224 to terminal 200.

As the amplifier shown in Fig. 2 has an odd number of stages, when a potential of one polarity with respect to ground is connected to the input terminal 200, the potential with respect to ground of the output mrminal 224 will be of the opposite phase, that is, the amplifier reverses the polarity of the potential applied to the input terminal 200.

Let a source of voltage e1 be connected through a resistor of resistance 11 to the input terminal 200, let the potential difierence between the terminal 200 and ground be e,;, the potential difference between terminals 224, 225 be e, the fraction of this potential applied to the feedback be Ke, the resistance of the feedback resistor be To and the voltage amplification of the amplifier be m.

The resistors 204, 205 impress a positive bias on the cathode of the twin triode 226, thus the control electrode of the twin triode 226 will not draw any current.

As the amplifier reverses the polarity with respect to ground of the applied voltage, a current i can flow from ground through the source 61; resistors T1 and r0; through the output circuit to round For a three stage amplifier, m may be 30,000 to 50,000, let m=40,000, K =1 and let To=71, then e=e1( )=O.9999 5e that is, the output voltage is very nearly equal to the input voltage.

Let the maximum value of e be say volts, then the maximum value of eg='.003 volt. That is, viewed from the source e1, the input circuit appears to have a very low impedance.

When K =1, and as issmall compared to m, Equation '1 will become circuit. that currents ii, iaio. now-in resist 1'1, rz. 2'0, and let K=1. As ee small. er=.i1r1.i ez=izrzi e=imii+iz=-iu thus and differentiating After the transient term has died down,

that is, the output. voltage-1: is proportional to the first derivative, or rate of change ef the applied voltage e1. r

If the current drawn by the load tends to reduce the output voltage of the am lifier, this reduction will cause a change in e which restores the output voltage to its original value. The amplifier thus acts as a constant voltage generator, and, viewed from the load, appears as a generator of very low impedance, generally as an impedance of about one ohm.

All of the amplifiers in the computer which are of the type shown in Fig. 2, are indicated by small triangles, the base representing the input circuit and the apex the output circuit, and are marked with a suitable symbol designating the quantity represented by the output voltage. ,The. sources I and M, Fig. 1, are of negative polarity; thus, due to the reversal of polarity, the output'voltage ofamplifier 302, Fig. 3, will be proportional to -+Do, the slant distance from the range finder, or radar, tothe present position of the target. 'A feedback resistor 303 is connected from the output to the input circuit of amplifier 302.

The output circuit of amplifier 302 is connected through resistor 304 to the input circuit ofamplifier 300, having a feedback resistor 30-5; 'The output voltage oi' amplifier 303 will .be propert-ionalto #130. "the negative of'theislant distance.

Range spot The output circuits of amplifiers 302., 306 are respectively'connected to the contacts of switch 301. The blade of switch 301 is connected through resistor "3'08 and the Winding 00] or potentiometer PTQ to ground. The brush "of potentiometer PTB is connected through resistor 3'l0to theinputcircuit of amplifier 302. When the blade of'switch 301 is ontheleft-hand contact, the output circuit of amplifier 302 is con"- nected; to ground throughthe winding'of p'oteni tiometer PT9 and the voltage selected by the brush .of'potentiometer PTH and supplied to the input circuit of amplifier'302 will'be of opposite polarity-to the voltage supplied to *resistor315, thus reducing the output voltage of amplifier 302. On the other hand, when the blade of switch 30"lis on'the'righthand contact, the'-volt= age supplied by the brush of potentiometer PTH is of the same polarity as the voltage "supplied to resistor *3i5 and increases the output voltage of amplifier 302. As the current supplied" to the winding of potentiometer PTS is proportional tothe slant distance, the ohangeproducedbyany given setting of potentiometerP'IB willbe, proportional tothe slant distance,- thus, a scale. graduated in "percentage of slant distance,-may beassociated'with the brush ofpotentiometer PTB.

If desirablepthe rangespot may be arranged to-change the slant distance by amounts expressed, say, 'in-yards. The contacts of switch 301 are disconnected from the outputeirouits of the amplifiers 302, 306 and connected to, the poles of a suitable source of power 3H, having anintermediate point grounded. In this case. a scale, graduatedin yards may be associated with the brush of potentiometer PTO.

In Fig. 130, O ist'he observation point'tothe present position of the target, a the vertical-pro jection of the targeton thehorizontal plane,

. Eothepresent elevationangle of the target, Ho

range of the target.

Then 7 Ho=Do sin E0 (4').

Ro==Docos E0 (5) The output circuit of amplifier 302, Fig. 13., is connected to ground through connection "312,. fourth set of break springsof, relay |'0,"F ig. 1, resistor .20, and the lower portion of the winding 503 of potentiometer PT5.

"The output circuitof amplifier 305, Fig. 3.35 connected to ground through connection 313, first set ofbreak springs of relay I9,Fig. Land the upper portion'of'the winding 503 of potentiometer PT5. An intermediate point in the Winding 503 isgrounded.

The potentiometer cards may be made by winding resistance wire closely and evenly ona strip of insulating material. One edge of this strip is straight and the wire crossing this edge is cleaned to make a good contact with the brush; "the other "edge of'the strip isshaped so that the width of the strip will vary to produce the desired functional variation in the resistance or" the winding. A single card, or a plurality'of cards placed end to end, is wrapped around :a light drum of suitable material, a continuous binding ring is placed roundthe card, or cards, and wedges mserted between the ring and card to press the card firmly to the drum. 'A plurality of drums of difierent diameters may be nested together and mounted on the outer portion of a suitable base, the potentiometer shaft may be journaled in a boss in the center of the base, and slip rings may be insulatingly mounted on the intermediate portion of the base, concentric with the shait. ,Brush arms, carrying brushes in contact with the straight edges of the cards and connected to other brushes in contact with the corresponding slip rings, are mounted (in the potentiometer shaft and may be driven directly by the shaft, or by gearing supported by the base and meshing with gears mounted on the shaft and brush arms.

In the circuit drawings, the cards of potentiometers which are automatically adjusted during the computations have been represented by circles surrounded by arcs indicating approximately the variations in the widths of the cards. Potentiometers which are preset for a given computation, or manually adjusted, are represented by straight cards, though these cards may also be formed into circles if desired. Each potentiometer has been given a PT number, e. g., PT23, and the associated cards numbered to correspond e. g., 2301, 2302 etc.

In the present computer, angles are measured in mils where 6400 mils is one revolution.

The brushes of potentiometer'PT5 are rotated by the elevation, or pointer, telescope, symbolically represented by the telescope 4 and associated gears. The card 503 extends over +1600 mils elevation and -200 mils depression, the

grounded tap representing mil or horizontal. The resistance of the resistor and the lower portion of the winding is equal to the resistance of the upper portion of the winding.

The winding of card 503 has a sinusoidal variation of resistance and, as the voltage supplied to the upper end of the card, corresponding to 1600 mils, is proportional to Da and the voltage supplied to resistor 20 is proportional to +Do, the voltage selected by the brush associated with card 503 is proportional to Do(- sin E0) that is, to HO The brush associated with card 503 is connected through resistor 16, second pair of break springs of relay l9, connection I! to the blade of switch 2!.

When ranging with a height finder, the synchronous transmitter driven by the height shaft of the height finder is connected to the synchronous receiver 7, driving the inner dial 8. The motor H, through the speed reducing devices 23 drives the brush associated with card 80l, PT8. and through suitable gears, represented by gears 24, 25, drives the middle dial 9.

. A grounded source of positive potential 25 is connected to ground through resistor 26 and the winding of card 80!. The brush of card 80l is connected through resistor 2! to the input circuit of amplifier 28, having a feedback resistor 31. The left-hand contact of switch 2| is connected through resistor 29 to the input circuit of amplifier 28, and a suitable meter is connected across the output circuit of amplifier 28. The operator adjusts the device 23 until the dial 9 tracks the dial 3, thus causing the brush of potentiometer PT8 to supply a voltage to the amplifier 28 proportional to +I-Io. The operator then adjusts the device l2 until the meter 30 reads zero. The voltage supplied to resistor 29 is thus made proportional to Ho, and, as the telescope 4 is tracking the target, the voltage selected by the brush of potentiometer PTO, will be proportional to -Do, the slant distance to the target.

In some cases, the height finder may not be at the same elevation as the reference point of the battery and a correction in height is required. A source of power 32, having an intermediate point grounded, has both poles connected to the contacts of a switch 33. The blade of switch 33 is connected to ground through resistor 34 and the winding of card 10I, PT]. The brush of potentiometer PT! is connected through resistor 35 to the input circuit of amplifier 28. The switch 33 is set to select a voltage of proper polarity, and the brush of potentiometer PT! is adjusted to select a voltage of proper magnitude, which, when supplied to resistor 35 will correct for the diiference in height.

Altitude spot The brush of potentiometer PT! may be adjusted to produce small arbitrary changes in the voltage supplied to the amplifier 28 which are equivalent to small changes in the voltage selected by the brush of potentiometer PT8.

When a height finder is not used, switch 2| may be placed on the right-hand contact, thus grounding connection I! through resistor '22, which has a resistance equal to the resistance of resistor 29.

The output circuit of amplifier 306, Fig. 3, is connected by connection 313, break springs of first pile-up of relay [9, Fig. 1, to the junction of cards 50L 502, potentiometer PT5. The outer end of card 501 is grounded; and the outer end of card 502 is connected to ground through resistor 36. Card 50! extends over an arc of 1600 mils; card 502 extends over an arc of 200 mils; the resistance of card 502 and resistor 36 being equal to the resistance of card 50l. The brush associated with cards 50!, 502 is placed at a right angle with respect to the brush associated with card 503, and is moved by the movement of the telescope 4. The windings of cards 501,

502 have resistance varying with a cosinusoidal function, and, as the voltage supplied by amplifier 306, Fig. 3, is proportional to --Do, the voltage selected by the brush associated with cards 50!, 502, Fig. 1, will be proportional to Do(- cos E0), that is, to Ro. Y

The brush associated with cards 50!, 502- is connected through resistor 31, break springs of second pile-up of relay l0, connection 38, resistor 320, Fig. 3, to the input circuit of an amplifier 321, Fig. 3, having a feedback resistor 322. The output circuit of amplifier 321 is connected through resistor 323 with the input circuit of' amplifier 324, having a feedback resistor 325.-

The output circuit of amplifier 324 is connected by connection 326, break springs of second pile-up of relay 39, Fig. 1, to the upper junction of cards 40I, 402, potentiometer PT4. The output circuit of amplifier 32I, Fig. 8, is connected by connection 321, break springs of fourth pile up of relay 39, Fig. 1, to the lower junction of cards 40!, 402, PT4. Cards.40l, 402 are arranged on the circumference of a circle.

As shown in Fig. 13A, the horizontal range R0 is resolved into the rectangular coordinates X0, Y0, having their origin at O, the point of observation. For convenience, the Yo coordinate is in the north-south line, and the X0 coordinate is in the east-west line, the azimuth angle A0 being measured clockwise from north. j 

